[PATCH] powerpc/powernv/pci: Fix build of pci-ioda.o

[PATCH] powerpc/powernv/pci: Fix build of pci-ioda.o

[Gustavo Romero]

Currently pnv_ioda_setup_bus_dma() is outside of a CONFIG_IOMMU_API guard
and if CONFIG_IOMMU_API=n the build can fail if the compiler sets
-Werror=unused-function, because pnv_ioda_setup_bus_dma() is only used in
functions guarded by a CONFIG_IOMMU_API guard.

That issue can be easily reproduced using the skiroot_defconfig. For other
configs, like powernv_defconfig, that issue is hidden by the fact that
if CONFIG_IOMMU_SUPPORT is enabled plus other common IOMMU options, like
CONFIG_OF_IOMMU, by default CONFIG_IOMMU_API is enabled as well. Hence, for
powernv_defconfig, it's necessary to set CONFIG_IOMMU_SUPPORT=n to make the
build fail, because CONFIG_PCI=y and pci-ioda.c is included in the build,
but since CONFIG_IOMMU_SUPPORT=n the CONFIG_IOMMU_API is disabled, breaking
the build.

This commit fixes that build issue by moving the pnv_ioda_setup_bus_dma()
inside a CONFIG_IOMMU_API guard, so when CONFIG_IOMMU_API is disabled that
function is not defined.

Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 26 +++++++++++------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 73a63efcf855..743d840712da 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1885,19 +1885,6 @@ static bool pnv_pci_ioda_iommu_bypass_supported(struct pci_dev *pdev,
 	return false;
 }
 
-static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe, struct pci_bus *bus)
-{
-	struct pci_dev *dev;
-
-	list_for_each_entry(dev, &bus->devices, bus_list) {
-		set_iommu_table_base(&dev->dev, pe->table_group.tables[0]);
-		dev->dev.archdata.dma_offset = pe->tce_bypass_base;
-
-		if ((pe->flags & PNV_IODA_PE_BUS_ALL) && dev->subordinate)
-			pnv_ioda_setup_bus_dma(pe, dev->subordinate);
-	}
-}
-
 static inline __be64 __iomem *pnv_ioda_get_inval_reg(struct pnv_phb *phb,
 						     bool real_mode)
 {
@@ -2501,6 +2488,19 @@ static long pnv_pci_ioda2_unset_window(struct iommu_table_group *table_group,
 #endif
 
 #ifdef CONFIG_IOMMU_API
+static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe, struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		set_iommu_table_base(&dev->dev, pe->table_group.tables[0]);
+		dev->dev.archdata.dma_offset = pe->tce_bypass_base;
+
+		if ((pe->flags & PNV_IODA_PE_BUS_ALL) && dev->subordinate)
+			pnv_ioda_setup_bus_dma(pe, dev->subordinate);
+	}
+}
+
 unsigned long pnv_pci_ioda2_get_table_size(__u32 page_shift,
 		__u64 window_size, __u32 levels)
 {
-- 
2.17.1

Re: [PATCH] powerpc/powernv/pci: Fix build of pci-ioda.o

[Oliver O'Halloran]

On Wed, Jul 29, 2020 at 8:35 AM Gustavo Romero <gromero@linux.ibm.com> wrote:
>
> Currently pnv_ioda_setup_bus_dma() is outside of a CONFIG_IOMMU_API guard
> and if CONFIG_IOMMU_API=n the build can fail if the compiler sets
> -Werror=unused-function, because pnv_ioda_setup_bus_dma() is only used in
> functions guarded by a CONFIG_IOMMU_API guard.
>
> That issue can be easily reproduced using the skiroot_defconfig. For other
> configs, like powernv_defconfig, that issue is hidden by the fact that
> if CONFIG_IOMMU_SUPPORT is enabled plus other common IOMMU options, like
> CONFIG_OF_IOMMU, by default CONFIG_IOMMU_API is enabled as well. Hence, for
> powernv_defconfig, it's necessary to set CONFIG_IOMMU_SUPPORT=n to make the
> build fail, because CONFIG_PCI=y and pci-ioda.c is included in the build,
> but since CONFIG_IOMMU_SUPPORT=n the CONFIG_IOMMU_API is disabled, breaking
> the build.
>
> This commit fixes that build issue by moving the pnv_ioda_setup_bus_dma()
> inside a CONFIG_IOMMU_API guard, so when CONFIG_IOMMU_API is disabled that
> function is not defined.

I think a fix for this is already in -next.

Re: [PATCH] powerpc/powernv/pci: Fix build of pci-ioda.o

[Gustavo Romero]

Hi Oliver,

On 7/28/20 7:50 PM, Oliver O'Halloran wrote:
> On Wed, Jul 29, 2020 at 8:35 AM Gustavo Romero <gromero@linux.ibm.com> wrote:
>>
>> Currently pnv_ioda_setup_bus_dma() is outside of a CONFIG_IOMMU_API guard
>> and if CONFIG_IOMMU_API=n the build can fail if the compiler sets
>> -Werror=unused-function, because pnv_ioda_setup_bus_dma() is only used in
>> functions guarded by a CONFIG_IOMMU_API guard.
>>
>> That issue can be easily reproduced using the skiroot_defconfig. For other
>> configs, like powernv_defconfig, that issue is hidden by the fact that
>> if CONFIG_IOMMU_SUPPORT is enabled plus other common IOMMU options, like
>> CONFIG_OF_IOMMU, by default CONFIG_IOMMU_API is enabled as well. Hence, for
>> powernv_defconfig, it's necessary to set CONFIG_IOMMU_SUPPORT=n to make the
>> build fail, because CONFIG_PCI=y and pci-ioda.c is included in the build,
>> but since CONFIG_IOMMU_SUPPORT=n the CONFIG_IOMMU_API is disabled, breaking
>> the build.
>>
>> This commit fixes that build issue by moving the pnv_ioda_setup_bus_dma()
>> inside a CONFIG_IOMMU_API guard, so when CONFIG_IOMMU_API is disabled that
>> function is not defined.
> 
> I think a fix for this is already in -next.

Indeed.

For the records, it's fixed in -next by:

commit e3417faec526cbf97773dca691dcd743f5bfeb64
Author: Oliver O'Halloran <oohall@gmail.com>
Date:   Sun Jul 5 23:35:57 2020 +1000

     powerpc/powernv: Move pnv_ioda_setup_bus_dma under CONFIG_IOMMU_API
     
     pnv_ioda_setup_bus_dma() is only used when a passed through PE is
     returned to the host. If the kernel is built without IOMMU support
     this is dead code. Move it under the #ifdef with the rest of the
     IOMMU API support.
     
     Reported-by: kernel test robot <lkp@intel.com>
     Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
     Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
     Link: https://lore.kernel.org/r/20200705133557.443607-2-oohall@gmail.com


Thanks.


Cheers,
Gustavo